Process Analyzers for Total Water Hardness


The WATERLINE GH process titrators are developed for the measurement of total hardness in boiler water, cooling water or potable water. The measurement principle is a complexometric titration of the water hardness with a special combination reagent which includes a buffer solution, the titrant solution and a hardness specific indicator. A photodetection system determines the titration end point (color change from red to blue). The result is displayed on the touchscreen as ppm CaCO3. The main applications for the analyzer are the survey and monitoring of water treatment plants and the analysis of drinking water.

The analyzer consists of a control unit with touchscreen and an analysis unit with a measuring chamber, valve, dosing pump (incl. stepper motor) and all required tube connections. The control unit includes a microprocessor which controls the automatic measurement incl. sampling, rinsing, titration and surveillance of the photodetection system. The analysis results can be used for the monitoring and control of a supervised process.

  • Automatic measurement incl. self test and drift compensation
  • Measurement ranges:
    WATERLINE GH05: 4 – 70 ppm CaCO3
    WATERLINE GH10: 30 – 350 ppm CaCO3
    WATERLINE GH20: 50 – 900 ppm CaCO3
    WATERLINE GH20: 50 – 900 ppm CaCO3
  • Easy operation via touchscreen
  • Adjustable limit value and alarm value
  • Programmable analog output (0/4-20 mA)
  • External start/stop of an analysis possible
  • No external calibration required.
  • Multi-range power supply (110–230 Volt,50–60 Hz) for variable use.
  • Including 2 polycarbonate wall cabinets (for control unit and analysis unit)
Parameter Total Hardness
Description Microprocessor-controlled analyzer for the determination of hardness in water
Typical Applications Monitoring and control of water treatment, water blending and potable water plants
Analysis Method Complexiometric titration of the total hardness using a combined reagent, comprising titer and hardness indicator
Type GH05 GH10 GH20
Measuring Range 4-70 ppm 30-350 ppm 50-900 ppm
Resolution 0,7 ppm 7 ppm 10 ppm
Accuracy 5 % of end value
Reproducibility 3 % of end value
Zero-point Stability automatic adjustment
Number of Samples 1
Operating Pressure0,1 - 10 bar
Temperature5 - 30 °C
Sample Volume25 ml per analysis (excluding rinsing)
Sample Conditionclear, with particles < 0.5 g/l ; < 50 µm
Chemical DemandspH 4 - 10, Fe < 3 ppm, Cu < 0,2 ppm, CO3 2- < 10 mmol/L
Drainpressure free into open drain
Number1, (optional 2)
Storage Temp.5 – 20 °C
Usage/analysishardness dependent
Reagent volume500 ml
Suitable forhardness dependent
Cycle (approx.)13 min., incl. rinsing
Sample interval1 – 99 min or external start/stop
Optional2nd pump (for cleaning solution)